The complexities of golf club design are well known. The specifications for each component of a club (i.e. the club head, shaft, hosel, grip, and subcomponents thereof) directly impact the performance of the golf club. Thus, by varying the design specifications, a golf club can be tailored to have specific performance characteristics.
Players utilizing metal wood type golf clubs have generally desired a golf ball trajectory that is longer and straighter, especially when compared to their iron type golf clubs. However, when a metal wood type golf club head is designed to maximize distance, it can sometimes do so at the expense of sacrificing accuracy. Hence, finding the correct balance of length and accuracy in a metal wood type golf club may be difficult, as numerous factors affect the length and accuracy of a metal wood type golf club.
Generally, a specific type of metal wood type golf club head called a “driver” has been used to maximize distances of a golf shot. Driver type golf club heads may achieve maximum distance by utilizing a variety of factors such as a longer shaft, a face having a higher coefficient of restitution (COR), a larger volume that is generally greater than 400 cc, a lighter material such as titanium, and a deeper face depth; resulting in a higher CG location due in part to its physical shape. Driver type golf club heads, because of their higher CG location combined with a deeper face depth, generally perform better off a tee. The focus on performance off a tee for the driver type golf club generally makes it more difficult for the driver type golf club head to hit a golf ball sitting on the ground without a tee; as the higher CG location of a driver type golf club head makes the sweet spot higher off the ground. Moreover, driver type golf club heads, although capable of maximizing the distance of travel of a golf ball upon impact, may generally suffer in terms of accuracy due to the increased shaft length as well as the increased face volume.
FIG. 1 shows a front view of a driver type golf club head 100 in accordance with a prior art metal wood type golf club head. Driver type golf club head 100, as shown in FIG. 1, illustrates the driver type golf club head 100 having a face 102, a hosel 104, and a shaft 106; wherein the driver type golf club head 100 has a CG 108 location that is at a distance d1 from the ground level 110. Face 102 in this prior art driver type golf club head 100 may have a plurality of scorelines 112 around the perimeter of the face 102. Scorelines 112 may generally be undesirable near the central impact portion of the face 102 as scorelines 112 decrease the overall thickness of the face 102, which in turn affects durability of the face 102. Face 102 in this prior art driver type golf club head may generally have a total face depth height of d11 measured from the ground level 110; wherein d11 may generally be greater than 55 mm from the ground level 110. This depth of face 102 of the prior art driver type golf club head 100 may generally be defined as the location of the earliest departure from the planer face 102 and it helps define the general profile and geometry of the prior art driver type golf club head 100 to yield a CG height to face depth ratio of greater than about 0.4.
It should also be noted that in this prior art driver type golf club head 100, the CG 108 location is relatively high off the ground level 110. This height distance d1 of CG 108 may generally be greater than about 20 mm off the ground 110, due to the large geometric shape of a driver type golf club head 100. A driver type golf club head 100 may generally have a club length of greater than about 44 inches, as the increased club length generally generates more distance through increased momentum. However, it is generally known in the art that increasing shaft length may generally have an adverse affect in decreasing the overall club accuracy for the golfer. Finally a golf ball 150 is shown in FIG. 1 to provide a reference of dimension of driver type golf club head 100 and CG 108 height d1 relative to a golf ball 150.
Turning now to FIG. 2, which shows a cross sectional side view of a prior art driver type golf club head 200 positioned behind a golf ball 250 wherein the CG 208 location of the prior art driver type golf club head 200 is at a distance d1 from the ground 210. The CG location 208 in a driver type golf club head 200, as shown in FIG. 2 may generally be higher than the height of the equator of the golf ball 250, making this driver type golf club head 200 difficult to hit a golf ball 250 that rests on the ground 210. In addition to the above, FIG. 2 may also show the face 202 of the prior art driver type golf club head 200 forming a loft angle α with a plane that is perpendicular to the ground 210. Loft angle α of this prior art driver type golf club head 200 may generally be between about 7.0 degrees to about 13.0 degrees resembling the low loft angles α that are typical for a driver type golf club head 200. This low loft angle α creates a low launching golf shot that is capable of maximizing the distance for a driver type golf club head 200. Finally, FIG. 2 shows a rounded leading edge 240 that is floating off the ground 210 generally found in a driver type golf club heads 200. This rounded leading edge 240 in a driver type golf club head 200 helps reduce weight at unnecessary locations that could be maximized elsewhere. Because driver type golf club heads 200 are generally only used to hit a golf ball off a tee, the leading edge 240 area may be shaved or removed without adversely effecting performance. However, if a driver type golf club head 200 is used to hit a golf ball 250 off the ground, this rounded leading edge may adversely affect the ability of a driver type golf club head 200 to interact with the turf making it difficult to hit a golf ball 250 of the ground 210.
Despite all the attempts to maximize distance of a golf shot, accuracy of a golf shot may be just as important; as golf balls that land in the rough areas of a golf course are more difficult to hit than those that land in the fairway areas of a golf course. Taller grass tends to push the club head off its intended path, and as blades of grass fall between the ball and the striking face, the added lubrication of the blades of grass decreases the friction and reduces the outgoing backspin of the golf ball. In order to address this differentiation in shot difficulty, many iron type golf club heads, especially wedge type golf club heads, have added aggressive groove configurations that help mitigate the loss in spin between a golf ball hit out of the rough when compared to a golf ball hit off of the fairway. Also, iron and wedge designs feature special sole widths and sole curvatures to help the golf club slide through the turf and keep the club head traveling along its intended path. However, despite all the advancements in iron type golf club heads to make shots out of the rough perform as well as shots hit out of the fairway, there still exists a dramatic difference in the shot difficulty; making accuracy of golf shots off the tee box an extremely desirable characteristic.
In order to address the decreased accuracy issue in driver type golf club head, some golfers use fairway type golf club heads to increase accuracy of their tee shots at the expense of sacrificing some distance when compared to a driver type golf club head. Fairway type golf club heads may generally achieve more accuracy than a driver type golf club head due in part to its shorter shaft, smaller volume of generally less than 400 cc, steel material, shallower face depth, and lower CG derived from its physical shape as well as higher lofts. Fairway type golf club heads, because of their lower CG location, shallower face depth, sharper leading edge, and forgiving sole curvatures, are generally capable of performing well when hitting a golf ball off the ground especially compared to a driver type golf club head. Despite their accuracy, fairway type golf club heads generally sacrifice significant distance when compared to driver type metal wood golf clubs due to their inherent properties such as being made out of a steel type material, having a lower COR, as well as having a shorter shaft.
FIG. 3 shows a prior art fairway type golf club head 300 having a CG location 308 that is at a distance d3 from ground 310. Fairway type golf club head 300 may generally have a CG location height distance d3 of less than about 17 mm. This distance d3 of a fairway type golf club head 300 is significantly lower than the height distance d1 depicting the CG location 108 of a driver type golf club head 100. (shown in FIG. 1) A fairway type golf club head 300 generally differs from a driver type golf club head 100 in that it has a shallower profile as shown in FIG. 3 with a total face depth d33 that is significantly lower than distance d11 shown in FIG. 1. Face depth height d33 may generally be greater than about 35 mm from the ground level 310. The shallower head profile of fairway type golf club head 300, combined with a smaller volume, shorter shaft, and the steel type material construction allows CG location 308 to be located below the golf ball 350, making it easier for fairway type golf club head 300 to perform when hitting a golf ball 350 off the ground 310. Ultimately, this face depth d33 and the CG height d3 may help define a CG height over face depth ratio of greater than about 0.4 as well.
Fairway type golf club head 300 may generally have a plurality of score lines 312 across the entire face 302, as durability of the face 302 of the fairway type golf club head 300 is generally less of a concern due to its steel construction. Although not shown in FIG. 3, fairway type golf club head 300 may generally have a higher loft angle of greater than about 13 degrees in order to create a higher trajectory for a golf ball 350 hit using a fairway type golf club head 300. A fairway type golf club head 300 may generally have a club length of about 42 inches to about 44 inches; as the shorter club length allows for more control. Finally, golf ball 350, as shown in FIG. 3, provides a reference of dimension of fairway type golf club head 300 and CG 308 height d3 relative to a golf ball 350.
It can be seen that both a driver type golf club head and a fairway wood type golf club head have their own separate and distinct advantages when compared to one another. However, both the driver type golf club head and a fairway wood type golf club have significant disadvantages associated with their inherent design, making the advantages of each almost mutually exclusive from one another. Hence it can be seen, there is tremendous advantage in the field for a metal wood type golf club head that can maintain the distance advantages of a driver type golf club head while having the accuracy and stability of a fairway type golf club head while also being capable of hitting a golf ball directly off the ground. More specifically, there is a need in the field for a metal wood type golf club head that has an increased performance characteristic that incorporates both the advantages of a driver type golf club head and a fairway type golf club head.